I had a user the other day contact me because they upgraded to Civil 3D 2017. They have a client who uses Vanilla AutoCAD 2015. They also have several other clients who have not yet made the move to 2017. He was having all sorts of issues with proxy objects appearing in his AutoCAD drawings. It appears that the process has changed slightly. In the past, we would just use the export tool from the application menu or the output tab (both are the same - EXPORTC3DDRAWING) and be able to open the exported AutoCAD file in Vanilla AutoCAD file and go forth from there able to work with the lines, arcs, circles, etc.
Here's what you need to do to get the Civil 3D 2017 drawing into AutoCAD format. It's a two step process. . .
First, let's get the file from Civil 3D 2017 to Civil 3D 2016 (or earlier version):
- In Civil 3D 2017, make note of the coordinate system of the drawing and then export the file to AutoCAD and Land XML
- In Civil 3D 2016 (or older version), begin a new drawing
- Assign the drawing the same coordinate system as the original drawing
- Insert the AutoCAD file (you’ll see you’ve lost all proxy objects; you will see no Civil 3D data)
- Insert the LandXML file
At this point you're still working with a Civil 3D drawing, just in an earlier format.
Now to get the drawing to AutoCAD:
Because of the fact that you lost those proxy objects in step 4, you'll need to proceed to the end of step 5. Then you can export the Civil 3D drawing to AutoCAD as you've normally done in the past. This export must be done in an earlier version of Civil 3D and not 2017.
UPDATE: Though it's not documented, I found that after the installation of Civil 3D 2017 Service Pack 1 the -EXPORTTOAUTOCAD issue in converting to AutoCAD linework has since disappeared and I can now take a Civil 3D 2017 drawing and export it to any version of Vanilla AutoCAD. It is still, and has always been, recommended that you follow steps 1 - 5 if you need to send a file back to earlier versions of Civil 3D.